Recent update had made my laptop unusable. Yoga start page appears then black screen. No login. I’ve tried all previous versions in the startup list. None work.
You have ‘previous versions in the startup list’?
Are you talking about different kernels in the GRUB menu? or snapshots?
If it were simply a broken config, or faulty plasmashell, then booting an older kernel or restoring the system snapshot from before the update should generally work.
But you say it’s ‘Bricked’ which means you couldn’t even boot from USB if you tried that?
What distribution are you using? KDE Neon? KDE Linux? If neither, head to their respective communications channels as they are not developed by the KDE project.